A vulnerable groundwater area is land where nitrate can move easily through soil and into groundwater. The criteria used to determine vulnerability include coarse textured soils, karst geology, or shallow bedrock. The USDA NRCS soils maps were used to determine coarse textured soils and shallow bedrock. Coarse textured soils are within 91 cm of the soil surface and soils with shallow bedrock in the soil profile are within 102 cm of the soil surface.
A Minnesota Department of Natural Resources Pollution Sensitivity of Near-Surface Materials Report was used to identify the locations of karst.
The application of nitrogen fertilizer in the fall and on frozen soils will be restricted in areas with vulnerable groundwater or DWSMAs that are at or exceed 5.4 mg/L nitrate-nitrogen. An area with vulnerable groundwater is an area where nitrate can move easily through soil and into groundwater.
The criteria used to determine vulnerability include coarse textured soils, karst geology, or shallow bedrock. View the interactive Vulnerable Groundwater Area Map to see where application of nitrogen fertilizer will be restricted. Vulnerable quarter sections are shown in purple and DWSMAs are in green on the map.
In areas where 50% or more of the quarter section has vulnerable groundwater or is in a DWSMA, with high nitrate, applications of nitrogen in the fall and on frozen soils will not be allowed in the entire quarter section. If less than 50% of the quarter section has vulnerable groundwater, the restrictions do not apply.
The application of nitrogen fertilizer in the fall and on frozen soils will be restricted in areas with vulnerable groundwater or DWSMAs that are at or exceed 5.4 mg/L nitrate-nitrogen. An area with vulnerable groundwater is an area where nitrate can move easily through soil and into groundwater.
The criteria used to determine vulnerability include coarse textured soils, karst geology, or shallow bedrock. View the interactive Vulnerable Groundwater Area Map to see where application of nitrogen fertilizer will be restricted. Vulnerable quarter sections are shown in purple and DWSMAs are in green on the map.
In areas where 50% or more of the quarter section has vulnerable groundwater or is in a DWSMA, with high nitrate, applications of nitrogen in the fall and on frozen soils will not be allowed in the entire quarter section. If less than 50% of the quarter section has vulnerable groundwater, the restrictions do not apply.
Yes, fall application of nitrogen fertilizer will be allowed in vulnerable groundwater areas or DWSMAs with high nitrate concentrations in wells, in the following situations*:
- to establish winter grains planted in the fall;
- for fall pasture fertilization;
- for perennial crops;
- for grass seed production;
- for cultivated wild rice;
- for research on fields 20 acres or less in size, or
- for growing fall cover crops within a potato rotation
*Must follow University of Minnesota nitrogen rate guidelines for each of the above.
There are additional exceptions and exemptions related to: soils with ultra-low permeability referenced in the rule; in areas with reduced leaching potential combined with a short spring planting season; and in counties where cropland makes up less than 3% of the total land area.
Ammoniated polyphosphate (MAP and DAP) and micronutrient formulations containing nitrogen can be applied as long as the applied rate does not exceed an average of 40 pounds of nitrogen per acre in a field. Fields with low or very low phosphorus levels, as determined by a certified lab, are exempt from this restriction.
Fall nitrogen fertilizer applications will also be allowed for agricultural research and demonstrations for academic purposes, provided the area is limited to 20 acres or less, or approved by the Commissioner of Agriculture.
These restrictions begin September 1, 2020.
Yes, fall application of nitrogen fertilizer will be allowed in vulnerable groundwater areas or DWSMAs with high nitrate concentrations in wells, in the following situations*:
- to establish winter grains planted in the fall;
- for fall pasture fertilization;
- for perennial crops;
- for grass seed production;
- for cultivated wild rice;
- for research on fields 20 acres or less in size, or
- for growing fall cover crops within a potato rotation
*Must follow University of Minnesota nitrogen rate guidelines for each of the above.
There are additional exceptions and exemptions related to: soils with ultra-low permeability referenced in the rule; in areas with reduced leaching potential combined with a short spring planting season; and in counties where cropland makes up less than 3% of the total land area.
Ammoniated polyphosphate (MAP and DAP) and micronutrient formulations containing nitrogen can be applied as long as the applied rate does not exceed an average of 40 pounds of nitrogen per acre in a field. Fields with low or very low phosphorus levels, as determined by a certified lab, are exempt from this restriction.
Fall nitrogen fertilizer applications will also be allowed for agricultural research and demonstrations for academic purposes, provided the area is limited to 20 acres or less, or approved by the Commissioner of Agriculture.
These restrictions begin September 1, 2020.
Mitigation is the action of reducing the severity of a problem. In addressing the problem of nitrate contamination, mitigation levels will be based on nitrate data collected from public wells.
Mitigation is the action of reducing the severity of a problem. In addressing the problem of nitrate contamination, mitigation levels will be based on nitrate data collected from public wells.
The MDA determines the mitigation levels for the DWSMAs of community supply wells based on monitoring data provided by the Minnesota Department of Health. All areas identified with elevated nitrate begin in a voluntary Mitigation Level (Level 1 or 2), unless the MDA determines there is a point source causing the well to exceed these levels or the MDA delays the determination of a mitigation level decision for good cause. A delay for good cause would allow MDA to collect additional information such as to evaluate a potential point source that may be a significant source of nitrate in the public well.
The process for determining the mitigation level includes conducting a review of the quality of the monitoring data, the condition and vulnerability of the well, the hydrogeology and groundwater flow paths for groundwater flowing into the well, and potential point sources such as an agricultural chemical facility, septic system(s), feedlot(s) or a poorly constructed well that may be contributing significantly to nitrate levels in the well. View the current list of Mitigation Level Determinations.
Level One
Community public water supply wells (and their DWSMAs) with monitoring results of 5.4 to less than 8 mg/L nitrate-nitrogen fall under Level 1. At this mitigation level the MDA will encourage the voluntary adoption of the University of Minnesota nitrogen fertilizer BMPs and other practices which can reduce nitrate levels in groundwater such as precision agriculture, perennial crops, forages, cover crops, nitrification inhibitors, new hybrids, or taking targeted land out of production. These other practices are collectively referred to as alternative management tools or AMTs. Approved AMTs may substitute for nitrogen fertilizer BMPs.
DWSMAs at mitigation Level 1 are subject to Part 1 of the rule but are not subject to Part 2 of the rule.
Level Two
Community public water supply wells (and their DWSMAs) with monitoring results at or exceeding 8.0 mg/L nitrate- at any point during the previous 10 years, or projected to exceed the drinking water standard of 10 mg/L nitrate-nitrogen in the next ten years, will be included in Level 2.
For DWSMAs at Level 2, the MDA will work with local farmers to adopt practices that can reduce nitrate levels in groundwater. A local advisory team will be formed to include local farmers, agronomists, and others to help recommend the BMPs and AMTs that should be used. In addition, a local groundwater monitoring well network may be developed. The MDA will promote the implementation of appropriate nitrogen fertilizer BMPs and AMTs. To help facilitate AMT implementation, the MDA has worked with other agencies to make DWSMAs with elevated nitrate among the highest priority areas for state and federal funding.
The MDA will conduct surveys to assess the adoption rates of BMPs and other practices and use computer modeling to estimate the change in nitrate losses over a DWSMA. The modeling will consider the soils, crops, agricultural practices and precipitation in the DWSMA and help local farmers estimate whether changes in practices will improve water quality.
Level Three
Level 3 is the first regulatory level. A Level 2 site will progress to Level 3 if one of the following occurs: after not less than 3 growing seasons or the estimated lag time, whichever is longer, the recommended BMPs are not adopted on 80% of the cropland acres (excluding soybean acres); or the nitrate concentrations in groundwater continue to increase; or, after not less than three growing seasons the residual soil nitrate below the root zone increases. The estimated lag time is the time it takes for changes in practices to have an effect on groundwater quality or on the public well with elevated nitrate. This time may vary significantly based on the local soils, hydrogeology and actual precipitation. Computer modeling and groundwater age estimates can be used to determine the estimated lag time. Residual soil nitrate testing below the root zone is a more difficult process of testing nitrate levels in soil. It is used to determine if nitrate is increasing or decreasing over time and may be used in locations with very long lag times.
The Commissioner of Agriculture – in consultation with a local advisory team – would then require landowners to implement actions such as BMPs, soil testing, record keeping, and educational programs. The Commissioner may delay moving to a regulatory level if computer modeling indicates that the adopted practices are going to be effective in reducing nitrate levels below 8 mg/L.
Level Four
Level 4 is the second regulatory level. If nitrate-nitrogen in the public water supply well exceeded 9 mg/L for any three samples in the previous 10 years; or after three years the residual soil nitrate below the root zone increases; or after three years or the estimated lag time, whichever is longer, the nitrate levels continue to increase, then the DWSMA would be given a Level 4 designation. The Commissioner of Agriculture – in consultation with a local advisory team – could require landowners to implement additional practices beyond best management practices. These practices would be determined on a site-specific basis following guidance outlined in MN Statutes Chapter 103H.275 Subd. 2(a). However, they shall not include restrictions on the primary crop or require fertilizer rates below the low end of the University of Minnesota recommended fertilizer rate range.
DWSMAs will be monitored and will move up or down a mitigation level according to changes in water quality. DWSMAs may only move up one mitigation level at a time. For example, a DWSMA will never go from Level 1 to Level 3 in a single cycle.
The MDA determines the mitigation levels for the DWSMAs of community supply wells based on monitoring data provided by the Minnesota Department of Health. All areas identified with elevated nitrate begin in a voluntary Mitigation Level (Level 1 or 2), unless the MDA determines there is a point source causing the well to exceed these levels or the MDA delays the determination of a mitigation level decision for good cause. A delay for good cause would allow MDA to collect additional information such as to evaluate a potential point source that may be a significant source of nitrate in the public well.
The process for determining the mitigation level includes conducting a review of the quality of the monitoring data, the condition and vulnerability of the well, the hydrogeology and groundwater flow paths for groundwater flowing into the well, and potential point sources such as an agricultural chemical facility, septic system(s), feedlot(s) or a poorly constructed well that may be contributing significantly to nitrate levels in the well. View the current list of Mitigation Level Determinations.
Level One
Community public water supply wells (and their DWSMAs) with monitoring results of 5.4 to less than 8 mg/L nitrate-nitrogen fall under Level 1. At this mitigation level the MDA will encourage the voluntary adoption of the University of Minnesota nitrogen fertilizer BMPs and other practices which can reduce nitrate levels in groundwater such as precision agriculture, perennial crops, forages, cover crops, nitrification inhibitors, new hybrids, or taking targeted land out of production. These other practices are collectively referred to as alternative management tools or AMTs. Approved AMTs may substitute for nitrogen fertilizer BMPs.
DWSMAs at mitigation Level 1 are subject to Part 1 of the rule but are not subject to Part 2 of the rule.
Level Two
Community public water supply wells (and their DWSMAs) with monitoring results at or exceeding 8.0 mg/L nitrate- at any point during the previous 10 years, or projected to exceed the drinking water standard of 10 mg/L nitrate-nitrogen in the next ten years, will be included in Level 2.
For DWSMAs at Level 2, the MDA will work with local farmers to adopt practices that can reduce nitrate levels in groundwater. A local advisory team will be formed to include local farmers, agronomists, and others to help recommend the BMPs and AMTs that should be used. In addition, a local groundwater monitoring well network may be developed. The MDA will promote the implementation of appropriate nitrogen fertilizer BMPs and AMTs. To help facilitate AMT implementation, the MDA has worked with other agencies to make DWSMAs with elevated nitrate among the highest priority areas for state and federal funding.
The MDA will conduct surveys to assess the adoption rates of BMPs and other practices and use computer modeling to estimate the change in nitrate losses over a DWSMA. The modeling will consider the soils, crops, agricultural practices and precipitation in the DWSMA and help local farmers estimate whether changes in practices will improve water quality.
Level Three
Level 3 is the first regulatory level. A Level 2 site will progress to Level 3 if one of the following occurs: after not less than 3 growing seasons or the estimated lag time, whichever is longer, the recommended BMPs are not adopted on 80% of the cropland acres (excluding soybean acres); or the nitrate concentrations in groundwater continue to increase; or, after not less than three growing seasons the residual soil nitrate below the root zone increases. The estimated lag time is the time it takes for changes in practices to have an effect on groundwater quality or on the public well with elevated nitrate. This time may vary significantly based on the local soils, hydrogeology and actual precipitation. Computer modeling and groundwater age estimates can be used to determine the estimated lag time. Residual soil nitrate testing below the root zone is a more difficult process of testing nitrate levels in soil. It is used to determine if nitrate is increasing or decreasing over time and may be used in locations with very long lag times.
The Commissioner of Agriculture – in consultation with a local advisory team – would then require landowners to implement actions such as BMPs, soil testing, record keeping, and educational programs. The Commissioner may delay moving to a regulatory level if computer modeling indicates that the adopted practices are going to be effective in reducing nitrate levels below 8 mg/L.
Level Four
Level 4 is the second regulatory level. If nitrate-nitrogen in the public water supply well exceeded 9 mg/L for any three samples in the previous 10 years; or after three years the residual soil nitrate below the root zone increases; or after three years or the estimated lag time, whichever is longer, the nitrate levels continue to increase, then the DWSMA would be given a Level 4 designation. The Commissioner of Agriculture – in consultation with a local advisory team – could require landowners to implement additional practices beyond best management practices. These practices would be determined on a site-specific basis following guidance outlined in MN Statutes Chapter 103H.275 Subd. 2(a). However, they shall not include restrictions on the primary crop or require fertilizer rates below the low end of the University of Minnesota recommended fertilizer rate range.
DWSMAs will be monitored and will move up or down a mitigation level according to changes in water quality. DWSMAs may only move up one mitigation level at a time. For example, a DWSMA will never go from Level 1 to Level 3 in a single cycle.
The MDA has the authority to regulate nitrogen fertilizer; the Minnesota Pollution Control Agency (MPCA) has the authority to regulate manure.
The rule calls for following the nitrogen fertilizer BMPs. One of the BMPs is to properly credit all nitrogen sources, including manure, when determining the nitrogen fertilizer rate.
